2001 Pontiac Grand Am with 2.4 liter engine was brought in with the SES light on and a complaint of tip in acceleration problem and rough idle. The codes that were stored were P0105 for a MAP sensor malfunction, P0172 for a system rich fault and P0300 for a general misfire fault. I opened the hood for a visual inspection and heard an unusual hissing sound. I followed it to a vacuum hose that ran from the intake to the MAP sensor. Removed the damaged hose and replaced with a new piece and problem is now gone.
The above picture is of course the bad hose and it is just normal wear and tear that caused this. Below is a picture of the MAP (sensor three wire connector) at top right of picture and the new vacuum hose (the second hose down from the connector)
The P0105 was obviously caused by the MAP sensor hose, the P0172 system rich was also caused by the faulty hose because the computer thought that the engine was running under a heavier load and the P0300 was caused by the unneeded rich condition (particularly at low rpm). I was especially happy that this was a simple fix as it is my daughters car!
Sparky’s the Man! He knows his stuff. Thanks for the posting Sparky. I had the same situation started with sligthtly rough idle for some time, hesitation started and just got worse. The the Service Engine Soon light would come on. Once it even turned off.
The OBD2 Reader was giving error code PO172, System to rich (Bank 1). I talked with a lot of people, even got professional options. Not one of them ever mentioned checking this little hose. My 2001 Grand AM SE 2.4L is purring like a kitten again, and it only cost me $1.07 out of pocket. Thanks again Sparky for the posting. I really appreciate it.
Ditto on the WIN! I had the exact same problem and got ‘advice’ to change the plugs, the coil packs, the plug sleeves and the injectors…luckily I only replaced the plugs which needed it anyway…plugged in a friends code reader and got P0172 and P0105. checked the hose to the MAP sensor and it basically was crumbling away…changed it for about a buck and instantly fixed the problem..THANK YOU!!!!!
You Da Man! That is exactly what was wrong with Z24 Cavalier.
A dealer mechanic replaced the coil pack and plugs and it didn’t fix this problem.
thank you so much for this post. all the other forums were pointing to all sorts of costly repairs. i just went outside and looked and that hose is split. definitely the problem. again thank you
This article is the win! My 2001 Grand AM SE 2.4L started with a slightly rough idle at stop lights some time ago. That has slowly developed into severe hesitation and occasionally the engine would die. I thought something was seriously wrong with my car. Turns out it was this little hose. $1.04 later, my car runs great. It was an instant and noticeable difference. Thanks you for the excellent pics. I was able to find and replace this part in no time.